The present invention relates to lubricants which are excellent in the effect on the reduction of friction.
Generally on the sliding surface of machinery, there is usually used fluid fats and oils, for example, oils or waxes. When these fluid fats and oils are used, a good sliding effect is exhibited on the normal operating conditions. On the other hand, at high temperatures or under heavy loading, problems have been occurred which are rupture of oil films on the sliding surface, frequent generation of seizure, or a remarkable drop in the efficiency of an engine.
In order to solve such kind of problems it has been proposed to disperse fine powder into the aforementioned fluid fats and oils.
For example, the lubricants have been developed wherein the resin derived from styrene, olefin or isoprene is mixed as a viscosity index improver in addition to disperse the fine powder of tetrafluoroethylene resin(polytetrafluoroethylene, hereinafter abbreviated as PTFE) which is one of the high-temperature resistant resin.
In this case, however, lubricating properties obtained are unsatisfactory when the heavy load is applied on the sliding surface. At high temperatures, 240.degree. C. and above in particular, fluorine based gas evolves as a result of thermal decomposition of PTFE. The gas causes corrosion of metal parts, ill effects on human bodies and moreover public hazards such as atmospheric pollution when PTFE is used for internal combustion engines.
On the other hand, various examinations have been carried out on the dispersed addition of finely powdered ceramics and yet further improvement in performance is desired in a similar manner as above.